12th annual...: dr. michael kallos & dr. samer adeeb kinnear centre kc 103 saturday 7:00 – 8:00 am...

12th Annual Alberta Biomedical Engineering Conference Program and Proceedings

October 21st – 23rd, 2011 The Banff Centre Banff, Alberta

We gratefully acknowledge the support of our sponsors for making this conference a success

C B R E

Centre for Bioengineering Research and Education Schulich Student Activities Fund BME Graduate Program

NSERC CREATE Training Program for Biomedical Engineers for the

21st Century

October 21 – 23, 2011 The Banff Centre

Banff, AB

PROGRAM COMMITTEE CONFERENCE ORGANIZERS Co-Chairs Michael S. Kallos, University of Calgary Nigel Shrive, University of Calgary Samer Adeeb, University of Alberta Marwan El-Rich, University of Alberta Albert Cross, University of Lethbridge Jon Doan, University of Lethbridge Larry Unsworth, Undergraduate Students Chair, University of Alberta Student Co-Chairs Swathi Damaraju, University of Calgary Garrett Melenka, University of Alberta

ABSTRACT REVIEWERS Jason Carey, University of Alberta - Technical Committee Lead Michael S. Kallos, University of Calgary - Technical Committee Lead Kajsa Duke, University of Alberta Marwan El-Rich, University of Alberta Nigel Shrive, University of Calgary Alison King, University of Calgary Elise Fear, University of Calgary Steve Boyd, University of Calgary Albert Cross, University of Lethbridge

Jon Doan, University of Lethbridge

UNIVERSITY OF ALBERTA

12th Alberta Biomedical Engineering Conference - Banff 2011

12th Alberta Biomedical Engineering Conference 2 POSTER JUDGES University of Alberta Doug Hill Martin Ferguson-Pell Kajsa Duke Marwan El-Rich University of Calgary Richard Frayne Leping Li Tannin Schmidt Kristina Rinker University of Lethbridge Jon Doan Sorina Truica

PODIUM JUDGES University of Alberta Vivian Mushahwar University of Calgary Jeff Dunn Wright University Thomas N. Hangartner

STUDENT VOLUNTEERS University of Alberta Garrett Melenka Organizing Great Challenge, volunteer at conference (co-chair

for podium sessions), Farhana Begum Volunteer at conference (co-chair for podium sessions) Jonathon Schofield Fundraising, volunteer at conference (co-chair for podium

sessions) Kamrul Islam Volunteer at conference (co-chair for podium sessions) Liping Qi Volunteer at conference (co-chair for podium sessions) Jiajie Wu Volunteer at conference (co-chair for podium sessions) Amin Komeili Volunteer at conference Charlie Hsue Fundraising University of Calgary Emily Bishop

Great Challenge, co-chair for podium sessions, coiling of programs, & general volunteer

Quinn Thompson Co-chair for podium sessions, coiling of programs Alireza Sojoudi Putting electronic programs on USB keys Taryn Ludwig Co-chair for podium sessions, coiling of programs Kiran Dwarkan Coiling of programs Saleem Abubacker Co-chair for podium sessions, coiling of programs Alyssa Randall Co-chair for podium sessions Swathi Damaraju Great Challenge, co-chair for podium sessions, coiling of

programs, & general volunteer Terri Semler Co-chair for podium sessions Kogan Lee Social night organizer Krishna

Panchalingam Fundraising

SPECIAL STAR University of Calgary Lisa Mayer Honorable Mention: Lorri Shaw

12th Alberta Biomedical Engineering Conference 3

PROGRAMME

Podium Sessions are in the Max Bell Auditorium. Poster Sessions are in the Max Bell 251 and 253. FRIDAY 4:00 - 8:30 pm REGISTRATION and CHECK-IN – Professional Development Center Front

Desk / Lounge 7:30 pm Opening Reception – Kinnear Centre KC 103

Welcome: Dr. Michael Kallos & Dr. Samer Adeeb Kinnear Centre KC 103

SATURDAY 7:00 – 8:00 am BREAKFAST – Vistas Dining Room 8:00 – 8:05 am Welcoming Remarks – Dr. Michael S. Kallos and Dr. Samer Adeeb 8:05 – 8:45 am Guest Speaker #1: Dr. Michael Buschmann, Ecole Polytechnique de Montréal

“Polymer-based delivery systems : molecular, cellular and disease model studies”

Session Chairs: Farhana Begum, University of Alberta & Taryn Ludwig, University of Calgary

8:45 – 9:55 am Student Podium Presentation Session #1 Session Chairs: Alisa Ahmetovic, University of Alberta & Swathi Damaraju, University of Calgary

Lewinson, Ryan 01 WEDGED FOOTWEAR INFLUENCES ON MECHANICAL RISK FACTORS

FOR RUNNING INJURY

Randall, Alyssa 02 Comparing the Effect of Diabetes and Ischemic Preconditioning on Conduction Reserve

Friesenbichler, Bernd 03 Reduced Elbow Extension Torque during Vibrations

Qi, Liping 04 Pushrim kinetics and coordination patterns of shoulder muscles on wheelchair propulsion for different propulsion techniques

Matthiasdottir, Sigrun 05 Muscle and fascicle excursions in children with Cerebral Palsy

Hunt, Megan 06 Fractal Methods for Evaluating Growth of Embryonic Stem Cells in Static Culture

12th Alberta Biomedical Engineering Conference 4 9:55-11:10 am Poster Session #1 (ODD NUMBERED POSTERS)

COFFEE/BEVERAGE BREAK Max Bell 251 and Max Bell 253 Judges: Drs. Doug Hill, Martin Ferguson-Pell, Kajsa Duke, Marwan El-Rich (University of Alberta); Drs. Richard Frayne, Leping Li, Tannin Schmidt, Kristina Rinker (University of Calgary); Drs. Jon Doan, Sorina Truica (University of Lethbridge)

Purdy, Michael 01 Stimulation of neurons using new microelectrode array design

Khurshid, Madiha 03 Bioreactor Seeding of Decellularized Tissue with Endothelial Cells

Jimenez, Jon 05 Optical Detection of White Matter Function in Multiple Sclerosis Patients

McCreary, Jennifer Keiko 07 Detection of Manganese by MRI Relaxation Ratio Mapping

Bartoshyk, Patrick 09 BIOMECHANICAL BASES FOR AN INCLUSIVE ICE SKATING EXERCISE PROGRAM FOR PEOPLE LIVING WITH PARKINSON’S DISEASE: PRELIMINARY CONCEPTS

Bigdely-Shamloo, Kamran 11 T-type Calcium channel Causes Calcium-Induced Calcium-Release In Smooth Muscle Cells

Kazemi Miraki, Mojtaba 13 Poromechanical Finite Element Study of the Articular Cartilage in Partial Meniscectomy Knee Joints

Barton, Kristen 15 Characterization of Cartilage Boundary Lubricant Composition and Function of Ovine Synovial Fluid Following Knee Surgery

Guo, Malinda 17 Tissue Status Monitoring using Near Infra-red Spectroscopy

Melnikov, Andrey 19 Continuum Mechanical Model of the Cardiac Muscle

Lee, Kovid 21 Modeling, Control, and Performance Assessment of Blood Plasma Glucose Concentration in Type I Diabetics

Tomic, Aleksandar 23 Numerical Implementation of a Large-Strain Model of Porous Fibre-Reinforced Tissues

Lee, Poh Soo 25 Engineering stem cell derived bone and cartilage in novel biomimetic bioreactor

Burgoyne, Steven 27 An Implantable Baroreceptor Stimulating Device; Its Ability to Improve Renal Blood Flow

Mishriki, Shahir 29 Assessing Arrhythmia Risk in Diabetic and Ischemic-preconditioned Rat Hearts

Obrejanu, Alexander 31 Fluid Flow Induced Cell Signaling in Cardiovascular Tissues

Woloschuk, Chris 33 A Posture Training Tool for Adolescents with Scoliosis

Enns-Bray, William 35 Difference in Active Joint Laxity between Dominant and Contralateral Knees of Healthy Individuals

Adair, David 37 3D Real-Time Magnetic Resonance Imaging Application to Visualize Contrast Inflow

Ghazanfari, Amin 39 Computer Modeling of Arrhythmia Vulnerability in Diabetic Cardiac Tissue

Komeili, Amin 41 A Way to Seek the Bijective Mapping of Morphological Changes

Lee, Nathanael 43 STRUCTURAL AND MECHANICAL CHARACTERIZATION OF THE ATRIA

Chizewski, Michael 45 The influence of calcaneal motion and tibial torsion on leg axial rotation


Sawatsky, Andrew 47 DOES KNEE EXTENSOR MUSCLE IMBALANCE CAUSE CHANGES IN PATELLAR TRACKING?

Semler, Terri 49 Adhesive Capabilities of Commercially Available Surgical Glues for the Repair of Defects in the Annulus Fibrosus

Wang, Mindan Wang 51 Fabrication and Characterization of 3D Alginate-HA Hydrogel Scaffolds for SCI Repair

Rodriguez Ramirez, Marcela 53 Removal of Motion Artifact in Cardiac Optical Mapping for Complete Heart Preparations

Andrews, Stephen 55 Strain Rate Dependence of Bovine Medial Menisci in Circumferential Tension

Chow, Alexandra 57 A 3-D HYDROGEL CELL SCAFFOLD FOR ASSESSING THE BIOCOMPATIBILITY OF INTRASPINAL MICROSTIMULATION ELECTRODES

11:10 – 12:30 pm Student Podium Presentation Session #2

Session Chairs: Jonathon Schofield, University of Alberta & Terri Semler, University of Calgary

Melenka, Garrett 07 Strain Measurement of Orthodontic Brackets using Digital Image Correlation

Moo, Eng Kuan 08 In-situ Chondrocyte Mechanics at Different Loading Rates: A Finite Element Study

Nathoo, Nabeela 09 Susceptibility weighted imaging reveals lesions in a mouse model of multiple sclerosis

Killick, Anthony 10 Contribution of the upper body to a unique gait transition in cross-country skiing

Chalmers, Eric 11 A Pressure Control System for Brace Treatment of Scoliosis

Abubacker, Saleem 12 Cartilage Boundary Lubricating Ability of Aldehyde Modified PRG4

Ahmetovic, Alisa 13 Update on clinical feasibility of the Smart-e-Pants for prevention of deep tissue injury

12:30 – 1:45 pm LUNCH – Vistas Dining Room 1:45 – 2:30 pm Industry Panel:

Shannon Boucousis ANT+ Design Engineer with Dynastream Innovations Inc. Diana Shaw Program Director - iRSM’s Continuing Professional Development Program Robert Little President at Altair Engineering Canada, Ltd.

Session Chairs: Garrett Melenka, University of Alberta & Alyssa Randall, University of Calgary

2:30 – 2:35 pm BREAK – Group Pictures

12th Alberta Biomedical Engineering Conference 6 2:35-3:50 pm Poster Session #2 (EVEN NUMBERED POSTERS)

COFFEE/BEVERAGE BREAK Max Bell Fish Bowl and Max Bell 253 Judges: Drs. Doug Hill, Martin Ferguson-Pell, Kajsa Duke, Marwan El-Rich (University of Alberta); Drs. Richard Frayne, Leping Li, Tannin Schmidt, Kristina Rinker (University of Calgary); Drs. Jon Doan, Sorina Truica (University of Lethbridge)

Nasr, Saghar 02 Mechanical Factors driving Stem Cell Differentiation in Fracture Repair: A Biphasic

FE Study of Collagen Scaffolds under Axial Compression and Bending Loads

Schofield, Jonathon 04 Knee-Ankle-Foot-Orthosis and Sit-to-Stand Biomechanics

Pansri, Siriporn 06 Molecular dynamic simulations for investigating protein adsorption to PEO surfaces

Mazloumfard, Farzaneh 08 The effect of tube wall stiffness on the speed of waves in tubes

Dwarkan, Sachitsing 10 Using the OpenCL (Open Computing Language) framework for medical image registration

Nobakht, Samaneh 12 A METHOD TO MEASURE RESIDUAL STRAINS IN THE MOUSE AORTA

Hoerzer, Stefan 14 A new methodology using Principal Component Analysis to quantify bilateral asymmetry of human gait

Twist, Elizabeth 16 Treatment of Deep Tissue Injury Using Intermittent Electrical Stimulation

Cheon, Jiin 18 Modeling the Hydrodynamics in Bioreactors for The Expansion of Embryonic Stem Cells

Kaur, Jaspreet 20 Sensitivity Analysis of Sinoatrial node

Buckley-Herd, Geoff 22 NORMAL AND OSTEOARTHRITIC SYNOVIAL STEM CELL-DERIVED TISSUE-ENGINEERED CONSTRUCTS RESPOND TO MECHANICAL STIMULUS FOLLOWING CHONDROGENIC DIFFERENTIATION

Koss, Kyle 24 MMP-2 Cleavable Peptide Hydrogel Delivery System Kinetics

Masala, Nemanja 26 Characterization of Recombinant Human PRG4 as an Ocular Surface Boundary Lubricant

Yamamoto, Maria 28 Rapid Serial Sarcomere Loss Caused by Electrical Stimulation in Rabbit Triceps Surae Muscles

Saevarsson, Stefan Karl 30 Kinematic Differences between Gender Specific and Traditional Femoral Implants

Steele, Robyn 32 Disturbed Flow Alters Nanoparticle Adhesion to Vascular Endothelial Cells

Thomson, Quinn 34 Toward an Automatic ASPECTS Method: Classification of Ischemic Brain Tissue on Non-contrast Computed-tomography Images with Image Texture Analysis

Lee, Estee 36 The Application of Prime Number-Sampling in Compressed Sensing Reconstruction

Begum, Farhana 38 Numerical Analysis of Augmented Locking Plate Fixation Repair for Proximal Humeral Fractures

Robertson, Jason 40 The Principle of Superposition During Lifting of an Object Exerting Two-Dimensional External Torques

Wu, Jiajie 42 A Variable Resistance Wheelchair Ergometer for Propulsion Biomechanical Studies Enders, Hendrik 44 Soft tissue vibration characteristics while treadmill running in shoes and barefoot

Little, Christopher 46 Hybrid Hydrogel/Polymer Scaffolds for Cartilage Tissue Engineering Applications Behradfar, Elham 48 Extending Purkinje System Model Using Fractal Structures


Zheng, Huayang 50 3D Knee Joint Modeling From MRI Images Akbari Shandiz, Mohsen 52 Effect of Pelvic Orientation on Radiographic Measurements of Acetabular

Inclination Baltich, Jennifer 54 Midsole Hardness, Gender & Age Effects on Lower Extremity Kinematics During

Running Sojoudi, Alireza 56 Spectral Clustering of Resting State fMRI Using a Group Similarity Matrix

3:50 – 5:00 pm Student Podium Presentation Session #3 Session Chairs: Garrett Melenka, University of Alberta & Emily Bishop, University of Calgary

Heik, Evelyn 14 Expansion of Skin-Derived Precursor (SKP) Cells to Promote Nerve Regeneration

Hamaliuk, Kenton 15 Development of a Long-Term Wheelchair Propulsion Instrumentation Device for Use in Evaluating Community Ambulation Parameters

Damaraju, Swathi 16 Investigations of Intercellular Communication in a 3-Dimensional Scaffold

Gallagher, Neal 17 Catheter Contact Geometry Affects Lesion Formation In Radio-frequency Cardiac Catheter Ablation

Yang, Run Ze 18 Assessment of acute ischemic stroke with near-infrared spectroscopy

Fortuna , Rafael 19 Effects of Electrical Stimulation on Muscles Injected with Botulinum Toxin Type A (Botox)

6:00 – 7:00 pm DINNER – Vistas Dining Room 7:00 pm “THE GREAT CHALLENGE” Max Bell Fish Bowl 7:15 pm Joint UA, UC, UL Faculty Meeting – Kinnear Centre KC 205 8:00 pm Social – Elk and Oarsman

119 Banff Avenue (2nd Floor, Above The Ski Hub) SUNDAY 7:15 – 8:15 am BREAKFAST – Vistas Dining Room 8:15 – 8:45 am Checkout 8:45 – 9:25 am Guest Speaker #2: – Dr. Thomas Hangartner, Wright State University

“Accurate Segmentation of Bone in Computed Tomography Images” Session Chairs: Liping Qi, University of Alberta & Quinn Thompson, University of Calgary

12th Alberta Biomedical Engineering Conference 8 9:25 – 10:20 am Student Podium Presentation Session #4

Session Chairs: Jiajie Wu, University of Alberta & Swathi Damaraju, University of Calgary

Ghazavi, Atefeh 20 A Finite Element Model for Extracellular Microelectrode Array Stimulation of Neurons

Islam, Kamrul 21 On Estimating Penetration Depth of the Patellofemoral Joint

Bishop, Emily 22 Differences in Active Muscular Control Between Dominant and Contralateral Knees in Healthy Individuals

Luk, Collin 23 A Novel Planar Patch-Clamp Microchip For Interrogating Synaptic Activity In Neurons

Rajaram, Ajay 24 A Preliminary Study on Living-Cell Scaffolds for Nerve Tissue Engineering

10:20-10:40 am Poster Session #3 (FINALISTS ONLY) COFFEE/BEVERAGE BREAK Max Bell 251 and Max Bell 253 Judges: Drs. Doug Hill, Martin Ferguson-Pell, Kajsa Duke, Marwan El-Rich (University of Alberta); Drs. Richard Frayne, Leping Li, Tannin Schmidt, Kristina Rinker (University of Calgary); Drs. Jon Doan, Sorina Truica (University of Lethbridge)

10:40 – 11:25 am Student Podium Presentation Session #5

Session Chairs: Kamrul Islam, University of Alberta & Saleem Abubacker, University of Calgary

Madden, Ryan 25 Chondrocyte Deformations under Extreme Tissue Strains

Beveridge, Jillian 26 Joint Damage Correlates with Abnormal Knee Kinematics in Sheep

Schipilow, John 27 Bone properties in elite male alpine skiers

Najari, Mohamad 28 Orthodontic Mini–Implant Orientation Effect in Load Bearing: Finite Element Analysis

11:25 – 11:30 am Closing Remarks – Dr. Samer Adeeb 11:30 – 12:00 pm Student-Led Activity Podium and Poster Prize Presentations – Sponsored by the NSERC CREATE

Training Program for Biomedical Engineers for the 21st Century NSERC CREATE Prize presentations for Most Outstanding Student Posters

Best Overall Poster, Most Creative Poster, Clearest Message Poster NSERC CREATE Prize presentations for Most Outstanding Podium Presentations

First Prize, Second Prize, Third Prize Canadian Society of Biomechanics/Société candienne de bioméchanique

Podium Presentation Prize Poster Presentation Prize


Map and Meeting Location

Accommodations – Professional Development Centre (PDC)

Registration and Check In Friday (PDC)

Opening Reception Friday (Kinnear Centre KC 103)

Accommodations – Lloyd Hall (LH)

Meals (Vistas)

Podium and Poster Sessions (Max Bell)


Directions to Elk and Oarsmen (Saturday Social) 119 Banff Avenue (2nd Floor, Above The Ski Hub)


Guest Speaker #1 – Dr. Michael D. Buschmann Canada Research Chair in Cartilage Tissue Engineering; Director Biomedical Science and Technology Research Group (FRSQ); Department of Chemical Engineering; Institute of Biomedical Engineering; Ecole Polytechnique de Montréal

“Polymer-based delivery systems: molecular, cellular and disease model studies” Abstract We have developed polymer-based systems for cartilage repair and for delivery of nucleic acids using chitosans. Chitosans are natural polymers of glucosamine and N-acetylated glucosamine, present in different proportions, sequences and molecular weight, all of which greatly influence its physicochemical and biological properties. The high safety profile of chitosans combined with our medical grade production and precise characterization permitted the discovery and development of a biomaterial for cartilage repair that has completed human clinical evaluation. More recent work in therapeutic delivery of nucleic acids uses nanoparticles that are electrostatic complexes of cationic chitosan with plasmid DNA (pDNA) or with small interfering RNA (siRNA). These systems have achieved high levels of transgene expression from pDNA and specific gene silencing using siRNA. A series of in vitro cell transfection studies revealed the importance of preparing specific chitosans, in terms of level of actetyl content and molecular weight, to obtain an optimal transgene expression. Live intracellular confocal imaging has provided mechanistic insight into the transfection process while physicochemical and nano-imaging have further allowed the establishment of structure/function relationships. These nanodelivery systems were then tested in vivo and shown to express the growth factors FGF-2 and PDGF-BB via subcutaneous and intramuscular administration. By further tailoring the type of chitosan used in these latter studies we were able to either stimulate or abrogate the generation of neutralizing antibodies to the transgene product, an important feature needed for effective delivery of therapeutic proteins by gene delivery. An important additional study has shown significant therapeutic potential of these systems in the delivery of glucagon-like peptide 1 in a small animal diabetes model where normalization of glucose metabolism in treated animals was achieved. Current efforts in this area are aimed at scale-up to clinical grade manufacturing and completion of proof of concept studies in distinct therapeutic areas. Brief Bio Michael Buschmann received a B. Engineering Physics from the University of Saskatchewan in 1984, and a Ph.D. in Medical Engineering and Medical Physics from the Division of Health Sciences and Technology at the Massachusetts Institute of Technology and Harvard University in 1992. His postdoctoral training in cartilage microscopy and histology was then completed at the University of Bern in Switzerland in 1994. Since 1994, Dr. Buschmann has established a multidisciplinary research program as Professor of Biomedical Engineering and Chemical Engineering at Ecole Polytechnique. The program focuses on the use of biomaterials to repair joint tissues including articular cartilage and meniscus and on the discovery and development of polymer-based gene and drug delivery systems for Diabetes, Cancer and Inflammatory diseases. (http://www.polymtl.ca/tissue/). He is one of the primary inventors of the BST-CarGel™ technology now in Pivotal clinical trial evaluation, and has been involved in founding BioSyntech (acquired by Piramal Healthcare Canada) and Biomomentum Inc, another Canadian start-up. Dr. Buschmann has published 101 articles, 219 conference proceedings and 15 patented or patent pending inventions. He is Director of the FRSQ Group in Biomedical Science and Technology and has received the Innovator Prize from the Quebec Association for Industrial Research (ADRIQ), the Melville Medal from the American Society of Mechanical Engineers (ASME), and an Award of Merit of the Canadian Arthritis Network of Centres of Excellence. He is a board member and scientific program committee member of the International Cartilage Repair Society.


Guest Speaker #2 – Dr. Thomas Hangartner Chair, Department of Biomedical, Industrial & Human Factors Engineering; Professor, Department of Biomedical, Industrial and Human Factors Engineering, Department of Medicine and Department of Physics, Wright State University, Dayton, Ohio

“Accurate Segmentation of Bone in Computed Tomography Images” Abstract Computed tomography (CT) is widely used in the assessment of bone parameters in live patients and animals as well as bone samples. Quantitative analysis requires the segmentation of the bone from the surrounding tissue, and most segmentation methods rely on some type of thresholding technique. Two types of information are of interest in bone analysis from images: geometric parameters and density parameters. We know from imaging theory that blurring is an inherent byproduct of all imaging methods. Depending on the threshold used for segmentation, the object boundary moves in space due to the sloping edge. It is, thus, critical to select the threshold that creates an object boundary that reflects the actual object size. Similarly, due to blurring, the imaged density shows erroneous values at the object boundaries. Such values must not be included for an accurate representation of the object density. Using a pQCT scanner and a bone phantom with known density and geometry, we show that the thresholds for geometry and density are different. The threshold for accurate geometric segmentation is around 50% of the difference of the densities between the adjacent tissues. The threshold for accurate bone density is around 95% of the maximum density value of the bone. However, for narrow bone structures, the imaged density values are below this threshold, and alternative approaches are necessary to extract the correct density values. The specific thresholds depend on the scanner and imaging parameters, and they need to be established based on phantom measurements. We show that the mechanical behavior of bone, tested under three-point bending and torsion, correlates highly with finite-element models extracted from CT images, using the appropriate thresholding approaches. Brief Bio A native of Switzerland, Dr. Thomas Hangartner is the director of the Biomedical Imaging Laboratory in Wright State University, Dayton, Ohio. After obtaining his doctorate degree from the Swiss Federal Institute of Technology, Zurich, Switzerland in Physics and Biomedical Engineering, Dr. Hangartner moved to Edmonton, Canada, to become a research associate and then an associate professor in the department of biomedical Engineering, University of Alberta. In 1986, Dr. Hangartner moved to Wright State University, Dayton, Ohio to become an associate Professor in the Department of Biomedical and Human Factors Engineering. At that time, he established the BioMedical Imaging Lab with an interest in the development of new methods designed to non-invasively measure bone density. The laboratory soon started to be involved in the clinical application of newly developed methods in measuring bone density. This has been taking place through laboratory-initiated research projects and through participation in clinical trials to test new drugs for osteoporosis and related diseases. Dr. Hangartner’s resume is decorated with several awards. Among them are: a distinguished professor of Biomedical Engineering Research; Outstanding Engineer and Scientist Award, Engineering and Science Foundation of Dayton; Fellow of the American Association of Physicists in Medicine; Honorary Chair, Imaging Science and Biomedical Engineering. In addition to his long track record of publications, Dr. Hangartner has different patents in the evaluation of bone strength using computer tomography.


Industry Panel Shannon Boucousis, ANT+ Design Engineer with Dynastream Innovations Inc. Shannon Boucousis is an ANT+ Design Engineer with Dynastream Innovations Inc., a wholly owned subsidiary of Garmin Int. and is responsible for developing ANT+ device profiles for interoperable, wireless devices in the health and fitness industry. Shannon graduated from the University of Queensland with a First Class Honours degree in Electrical and Electronic Engineering. She also participated in an international student exchange program and an internship program, both with the University of Calgary. Through her internship position with TRLabs, Shannon was involved in cutting edge wireless technology research, leading to her Honours thesis on emerging Wifi technology, and eventually a position as an RF applications engineer for Cisco Systems in Sydney, Australia. Shannon left Cisco Systems to pursue a personal interest in equestrian, training with Olympic level athletes in the United Kingdom, Europe and North America. She then returned to the University of Calgary to pursue an MSc at the University of Calgary, with an emphasis on electrical/biomedical engineering, specifically in the field of medical imaging. Shannon then worked as a research assistant to Dr Steven Boyd (University of Calgary) managing research on bone health in the general population, as well as various animal and patient studies. Dynastream develops a variety of personal monitoring products, and has also developed ANT, a proprietary ultra low power wireless communications protocol. The ANT+ Alliance includes over 400 companies worldwide, such as Timex, Adidas, Garmin and many more. Shannon’s role as an ANT+ design engineer involves working with these member companies and designing interoperable, wireless connectivity between their health and fitness monitoring products.


Industry Panel Diana Shaw - Program Director - iRSM’s Continuing Professional Development Program

Originally from London, UK, Dr. Shaw obtained her M.Sc. in Biotechnology at the University of Queensland, Australia, and completed her Ph.D. in Medical Genetics at the University of Calgary.

After 2 post-doctoral positions at the University of Alberta (Analytical Chemistry and Medical Microbiology and Immunology), Dr. Shaw decided to venture into the business side of science and completed a WestLink Technology Commercialization Internship, providing working experience in technology transfer, venture capital, law and high tech/spin off companies. Subsequently, Dr. Shaw was hired by Ceapro (an Edmonton-based small public healthcare company) in 2003 as Manager, Business Development then in 2006, Dr. Shaw moved to the Alberta Research Council as Director of Business Development and Marketing for Life Sciences, focusing on product development for Alberta-based biotechnology companies.

In 2007, Dr. Shaw accepted the position as Director of Business Development at the Institute for Reconstructive Sciences in Medicine (iRSM). In addition to her business development role, Dr. Shaw manages the services provided by iRSM’s Medical Modeling Research Laboratory (MMRL). She coordinates the Research Services at iRSM, which has a unique translational clinical-research environment, an interdisciplinary team (including computing, engineering, industrial design, clinicians and surgeons), and access to facilities industry, healthcare and academic partners, as well as the digital design and rapid prototyping technologies in MMRL. She is the Program Director for iRSM’s Continuing Professional Development Program, which encourages knowledge translation and dissemination in the applications of advanced digital technologies in reconstruction and rehabilitation. The Institute for Reconstructive Sciences in Medicine (iRSM)

The Institute for Reconstructive Sciences in Medicine (iRSM) is an internationally recognized clinical and research institute focused on medical reconstructive sciences. It is a joint initiative of the University of Alberta, Alberta Health Services and the Covenant Health.

iRSM’s decade long international reputation for innovation and advances in patient care and research has been earned by combining expertise in disciplines such as surgery, medicine, dentistry, rehabilitation medicine, engineering and computing science to create a fully integrated environment for clinical care, research, education and training in reconstructive medicine and technology. As an international referral centre, it is a leader in the complex area of osseointegration (bone) implanted devices for prosthetic replacement of skull and facial defects resulting from cancer, trauma and congenital conditions.

iRSM has a reputation as a pioneer in the application of advanced technologies to support clinical and research activities. A fundamental mandate for iRSM is the development and application of new knowledge for the advancement of medical practices and quality health care. iRSM’s innovative research model is comprised of multi-disciplinary teams across five faculties at the University of Alberta and extends to a number of international collaborations at leading institutions and industrial partners around the world. Research at iRSM involves both basic science and applied research. The developments taking place at iRSM are rapidly advancing Canada to a position of strength in the advancements of science and technology development for the benefits of Canadians requiring head and neck surgical care, and to develop products for the $260 billion international medical device market.

iRSM actively seeks industry, institutional and independent partners. We offer access to technologies and products with a range of clinical and prototype readiness, world-class interdisciplinary researchers, and development project opportunities.


Industry Panel Robert B. Little – President, Altair Engineering Canada, Ltd. Robert Little is the president of Altair Engineering Canada, Ltd. As the senior Canadian and a long-time employee at Altair, Little was asked to form Altair Canada in 2005, making it the company’s fourteenth global subsidiary. The focus on Canada has allowed him to connect with Canadian universities, government organizations and manufacturing companies across a number of industries, including automotive, aerospace, rail, consumer products and heavy equipment.

Little earned a bachelor of applied science degree, followed by a master of applied science degree in mechanical engineering from Queen’s University in Kingston, Ontario. He went on to earn a masters degree in business administration from the University of Michigan in Ann Arbor. Interestingly enough, it was finite element analysis research in the area of orthopaedic biomechanics for his engineering master degree that enabled him to get an early start applying the same technology for Altair’s clients in the 1980’s.

Little and his wife Debra have three sons and live in Windsor, Ontario. He is currently a board member of the AUTO21 Network Centre of Excellence and the SHARCNET High Performance Computing Consortium in Canada, and is Manufacturing Subcommittee Chair for the Windsor Essex Economic Development Commission. Altair Engineering Canada, Ltd. A leading global provider of technology that strengthens client innovation Altair Engineering, Inc. empowers client innovation and decision-making through technology that optimizes the analysis, management and visualization of business and engineering information. Privately held, with more than 1,300 employees, Altair has offices throughout North America, South America, Europe and Asia/Pacific. With a 20-year-plus track record for product design, advanced engineering software, grid computing technologies and enterprise analytics solutions, Altair consistently delivers a competitive advantage to customers in a broad range of industries. Altair Engineering's HyperWorks is a computer-aided engineering (CAE) simulation software platform that allows businesses to create superior, market-leading products efficiently and cost effectively. HyperWorks accomplishes this in two significant ways: * A flexible software licensing model that replaces expensive traditional licensing plans with a pay-per-use system. Employees across organizational and geographic boundaries will be able to access simultaneously not only the HyperWorks suite, but also a broad range of complementary third-party programs and other Altair products at no extra cost. * Simulation-driven design technologies that enables achievement of performance, timing, and cost targets through rapid, low-cost, virtual exploration that accelerates informed decision making throughout the product life cycle. Altair Engineering Canada, Ltd. is a wholly-owned subsidiary of Altair Engineering, Inc. in Troy, Michigan.


NOTES:

Podium Presentation Abstracts

WEDGED FOOTWEAR INFLUENCES ON MECHANICAL RISK FACTORS FOR RUNNING INJURY *Ryan T. Lewinson, Jay T. Worobets & Darren J. Stefanyshyn

Human Performance Laboratory, University of Calgary, Calgary, Alberta, *[email protected]

Introduction

Approximately 50% of all runners will

develop a running-related injury in a

given year [1,4]. In an assessment of

biomechanical risk factors for running

injury, Stefanyshyn et al. [3] found that

healthy subjects who experience increased

knee abduction moments-of-force (KAMs)

and increased knee external rotation

moments-of-force (KXMs) during running

are more likely to develop a running injury

over a six month period. Therefore, one

possible approach to running injury

prevention is minimizing the KAM and

KXM magnitudes that runners experience.

Knee joint moments can be reduced

during walking using wedged footwear [2];

however, their effects during running remain

unknown. The purpose of this study was to

determine the effects of medially and

laterally wedged footwear on KAMs and

KXMs during running.

Methods

Nine healthy male subjects volunteered to

participate in the study (age: 25±3 years;

mass: 76±5 kg; height: 178±7 cm). Three

retroreflective markers were placed on each

of the right shoe, shank and thigh segments

of each subject. Subjects were then asked to

complete 5 trials running at 4m/s with each

of 3 footwear conditions: neutral shoes with

(1) no insert, (2) a 9mm medial wedge

insert, and (3) a 9mm lateral wedge insert.

Body segment kinematics and ground-

reaction kinetics were recorded

simultaneously during each trial using an 8-

camera Motion Analysis system at 240 Hz,

and a Kistler force platform at 2400 Hz,

respectively.

A standard inverse dynamics approach

was used to calculate the peak KAMs and

KXMs for each subject and footwear

condition. Footwear conditions were

compared by one-way repeated-measures

ANOVA (α=0.05). Paired t-tests with

Bonferroni corrections were used for post-

hoc analysis.

Results

Peak KAMs (p=0.001) and peak KXMs

(p=0.037) were significantly different across

footwear conditions. KAMs decreased by

12% with lateral wedge use and increased by

13% with medial wedge use during running.

KXMs were decreased by 16% with lateral

wedge use and increased by 16% with

medial wedge use during running (Figure 1).

Figure 1. Mean(S.D.) knee joint moments (n=9) for

each footwear condition. * indicates p=0.002.

Conclusions

Laterally wedged footwear can decrease

peak knee abduction and external rotation

moments during running, while medially

wedged footwear does the opposite. It is

recommended that laterally wedged

footwear be tested as an intervention for

healthy runners to determine if incidence of

running injury can be reduced.

References

1. Matheson, G.O. et al. (1989). American Journal of Sports Medicine.

2. Radzimski, A.O. et al. (2011). The Knee. 3. Stefanyshyn, D.J. et al. (2001). Proceedings of

the 5th

Symposium on Footwear Biomechanics.

4. van Mechelen W. (1992). Sports Medicine.

12th ALBERTA BIOMEDICAL ENGINEERING CONFERENCE

PODIUM PRESENTATION #1

Comparing the Effect of Diabetes and Ischemic Preconditioning on Conduction Reserve 1A Randall, 2,3,4A Nygren

1Biomedical Engineering Graduate Program, 2Dept. of Electrical & Computer Engineering, 3Centre for Bioengineering Research and Education, and 4

Libin Cardiovascular Institute, University of Calgary

Healthy heart tissue has a large conduction reserve, i.e., many gap junctions can become non-functional without affecting the speed of electrical propagation in the tissue. Our lab has demonstrated that diabetes induced with Streptozotocin (STZ) causes disorganization of gap junctions, resulting in a decrease of the conduction reserve of the tissue [1].

Introduction

The observation that brief episodes of ischemia can activate protective mecha-nisms, allowing the heart to better withstand subsequent longer-duration ischemia, is known as ischemic preconditioning (IPC). Literature results have shown that IPC causes a similar disorganization of gap junctions [2] indicating a similar mechanism may be involved in STZ and IPC. The purpose of this work is to compare conduction reserve in IPC and STZ treated tissue.

Animals were divided into 4 groups; Control, Control with STZ induced diabetes, IPC and IPC with STZ. Animals were euthanized; their hearts excised and perfused with a Kreb’s buffer using the Langendorff method. After a 20 min stabilization period, IPC hearts were subjected to two episodes of stopped flow for 3 min followed by 5 min reperfusion. Control hearts were continually perfused for the same length of time.

Methods

Two different trials were completed for each of the 4 groups: 1) a measure of conduction reserve was obtained by determining the effect of high extracellular K+ on the tissue’s activation time (AT) (inversely proportional to speed of conduction); and 2) the response of the AT to ischemia was measured 2 and 5 min into a third and final ischemic episode. In both experiments, ATs were normalized to the value obtained immediately prior to increasing [K+] and onset of ischemia, respectively. AT was evaluated using optical mapping techniques [1].

Experiment 1: Normalized activation times (NAT) shows a significant depletion of conduction reserve in STZ however IPC has no significant effect on the conduction reserve of either Control or STZ hearts. IPC did have the trend (not statistically significant) to increase NAT in controls by 11% and decrease NAT by 8% in STZ.

Results

Experiment 2: STZ+IPC and IPC NAT in response to the IPC protocol were not statistically different. NAT is shown for 2 and 5 min ischemia in Figure 1. NAT STZ and STZ+IPC were significantly higher than control for the first 2 min ischemia however not at 5 min. Inversely IPC was not significant at 2 min ischemia but was at 5 min.

IPC and STZ have a similar slowing of conduction velocity in response to ischemia.

Conclusions

IPC appears to have no significant effect on conduction reserve of the tissue (assessed with high [K+

These results indicate that while similar mechanisms may be activated in STZ and IPC, their interaction is complex. A longer IPC protocol should be tested to clarify the effects of IPC.

]), while previous STZ treatment does. Against our hypothesis, the IPC protocol applied to STZ tissue has a trend to decrease the AT (thus increasing the conduction reserve of the tissue).

[1] PMID: 21037228 References

[2] PMID:18519446

Figure 1: Experiment 1, NAT at 2 and 5 min isch. Figures

*p>0.05 with respect to Control

* * *



Reduced Elbow Extension Torque during Vibrations Bernd Friesenbichler

1, Aurel Coza

1, Benno M. Nigg

1

1Human Performance Lab, University of Calgary, 2500 University Dr NW, Calgary, AB, Canada, T2N 1N4

Introduction: Soft tissue vibrations are

often the result of impacts during walking,

running, skiing and other physical activities.

The acute effects of vibrations on force

generation have rarely been tested and are

generally little understood. A systematic

study of muscle force production and its

dependency on superimposed vibrations

could help researchers to tune vibration

characteristics in order to modify contraction

strength and efficiency. The current study

investigates the influence of systematically

changing vibration frequency on maximum

elbow extension torque and muscle activity.

Methods: A pneumatic vibrator was mounted onto the

crank of a dynamometer which allowed for

the superposition of longitudinal vibrations

transmitted to the forearm of the subjects.

Fifteen healthy female subjects were

instructed to perform a series of maximal

voluntary isometric contractions (MVCs)

against the crank (elbow extension). The

upper arm to forearm angle (elbow angle)

was set at 60, 90 and 120 degrees (where

180 deg = full extension). At each angle,

subjects performed one control MVC

without vibrations and three MVCs with

vibrations at different vibration frequencies.

Extension torque was quantified by the

dynamometer; vibration frequency and

amplitude were quantified using an

accelerometer attached to the bony part of

the wrist. Muscle activity (EMG) of the

triceps and biceps brachii, and extension

torque in vibration and non-vibration trials

were recorded and compared using a paired

Student’s t-test (p < 0.05) and Pearson

correlation coefficients were used to

correlate torque and muscle activity to

vibration frequency.

Results:

The vibration frequency ranged between 20

and 40 Hz at an average vibration amplitude

of 5.9 mm ± 2.25 mm (peak to peak) at the

wrist level. During vibration exposure,

maximal torque decreased significantly

relative to non-vibration control by 1.8 % (±

5.7 %), 7.4 % (± 7.9 %) and 5.0 % (± 8.2 %)

at 60, 90 (Fig. 1) and 120 deg, respectively.

Correlation of torque to frequency changes

were between r2 = 0.014 and 0.116 and not

significant. Muscle activity during vibration

exposure increased significantly in both,

triceps (agonist) and biceps (antagonist) by

~ 30 to 40 % (Fig. 1) at each elbow angle

and the correlation to frequency was

between r2 = 0.000 and 0.09 and not

significant.

Discussion and Conclusions: One potential reason for the surprising

finding may be that roughly equal increases

in muscle activity produce different

moments about the elbow joint since the

moment arms of tri- and biceps change at

each elbow angle but clearly not by the same

magnitude. At 60 deg, the difference in

moment arm length is small (~0.4cm), but at

90 and 120 deg, the difference increases

about five-fold (~2.0cm) [1] in favor of the

biceps (antagonist) und thus may produce a

larger counter-moment during vibrations.

The data revealed that, depending on the

elbow angle but independent of vibration

frequency, maximal extension torque

dropped during vibration exposure although

muscle activity increased in tri- and biceps.

References: [1] Murray W, Delp S, Buchanan T. J Biomech 28,

513-525, 1995.

Figures:

Figure 1: Maximum extension torque and muscle activity

at 90 deg elbow angle (p < .01).



Pushrim kinetics and coordination patterns of shoulder muscles on wheelchair propulsion for different propulsion techniques

Liping Qi1, James Wakeling2, Simon Grange1, Martin Ferguson-Pell1 1Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada, T6G 2G4 2Department of Biomedical Physiology and Kinesiology, Simon Fraser University, BC, Canada, V5A 1S6

Individuals undergoing treatment for a spinal cord injury (SCI) learn to use a wheelchair as soon as they are stable and able to sit up without complications. However the use of a wheelchair, which is intended to restore mobility, may not be without risk. Upper limbs of wheelchair users are subjected to unnatural loading conditions and repetitions of use. Over time, shoulder joints associated with the upper limbs of manual wheelchair users inevitably deteriorate. One recommendation to patients in the clinical practical guidelines for the preservation of upper limb function following spinal cord injury is that for each propulsion stroke their hands move in a semicircular pattern and continue below the pushrim in the recovery phase [1]. For our study, a short propulsion technique instruction session was designed to examine the effects of the semicircular motion technique on wheelchair biomechanics, shoulder muscle coordination patterns in particular. Our hypothesis is that muscle recruitment for semicircular motion propulsion will elicit significant changes in muscle coordination patterns compared to those for self-selected propulsion techniques.

Introduction

15 able-bodied participants (8 males, 7 females, age: 30±4 years, weight: 65±12 kg) volunteered to participate in this study. Surface electromyography (sEMG) activity of 7 upper extremity muscles was recorded using parallel-bar EMG Sensors. The SMARTWheel (Three Rivers Inc., LLC, Mesa, AZ, USA) was used for the collection of kinetic data. The wheelchair kinetics and EMG activities of 7 muscles were recorded during wheelchair propulsion on an ergometer with a self-selected propulsion technique and a semicircular technique. The kinetics variables, and the onset, cessation, duration of EMG activity from 7 muscles

were compared for 2 sessions with paired t-test. Muscle coordination patterns across 7 muscles were analyzed by principal component analysis (PCA) [2, 3].

Methods

The push frequency was significantly lower (P

Muscle and fascicle excursions in children with Cerebral Palsy 1Sigrun Matthiasdottir, 1Marlee Hahn, 1Megan Yaraskavitch, 1Walter Herzog

1

Human Performance Lab, University of Calgary, Canada

Cerebral Palsy (CP) is a static lesion in the brain that happens before, during or shortly after birth. It is a non-progressive disorder that leaves children with permanent motor impairments [1]. Many children with CP have spasticity. Joint contractures often form when spastic muscles become taut and inhibit the full range of motion (ROM) of the joint [2]. The detailed reasons for why muscles become taut remain unknown. It has been suggested in some studies that short fascicle lengths (FL) in spastic muscles cause tightening [3] but other studies do not confirm these findings [4]. The purpose of this study was to measure FL and muscle and fascicle excursions of the medial gastrocnemius (MG) for the full passive ROM of the ankle in children with CP and typically developing (TD) controls.

Introduction

The experimental group included 9 children with CP between the ages of 8 and 16. The control group included 14 age and sex-matched TD controls. The children were seated in the chair of a Biodex

Methods

TM

System III dynamometer and their foot was strapped to a footplate. EMG electrodes were placed on the MG and the tibialis anterior muscles. An ultrasound probe was fixed to the lower leg to visualize the myotendinous (MT) junction first and the mid-belly of the MG muscle second. Torque, ankle angle and EMG data were collected for four passive trials covering the full ROM of the ankle joint. A common ROM was defined as the range from the lowest maximum dorsiflexion to the lowest maximum plantarflexion found between all subjects. Fascicle lengths and MT displacements were measured from the ultrasound images. In cases where fascicle lengths were not fully visible, trigonometric relationships were used to calculate fascicle lengths from the measured pennation angle (α) and muscle thickness (Tm). Non-parametric Mann-Whitney U-statistics (α=0.01) were used to test for differences between groups.

The common ROM was 87-126°. Fascicle lengths at all ankle angles were shorter for CP children (Figure 1), while fascicle excursions over the common ROM were not significantly different from TD control subjects. However, fascicle excursions as a percent of resting fascicle lengths were significantly greater for CP subjects. Muscle-tendon excursions over the common ROM were greater for control group subjects. Fascicle excursions as a percentage of muscle-tendon excursions were greater in children with CP compared to TD controls.

Results

Our results confirm previous findings that FL are shorter in children with CP compared to TD children. We also show that fascicle excursions relative to fascicle lengths and muscle-tendon excursions are greater in children with CP over a universal ROM. This novel result has important implications for the impairment of function in CP children during everyday movements.

Conclusions

1. Campell SK. Decision Making in Pediatric Neurologic Physical Therapy. Philadelphia: Churchill Livingstone, e89-97,1999

References

2. Pontén E, et al. Muscle and Nerve 36, 47-54, 2007. 3. Mohagheghi AA, et al. Developmental Medicine and Child Neurology 50, 44-50, 2008. 4. Malaiya R, et al. Journal of electromyography and Kinesiology 17, 657-663, 2007. Figures

Figure 1: Fascicle lengths

*



Fractal Methods for Evaluating Growth of Embryonic Stem Cells in Static Culture Megan M. Hunt1,2, Ian D. Gates2, Michael S. Kallos1,2

1Pharmaceutical Production Research Facility, Schulich School of Engineering, University of Calgary, Alberta 2

Dept. of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, Alberta

Ultimately, tissue engineering aims to repair and heal diseased tissues. The building blocks used in tissue engineering are living cells or cell aggregates. Embryonic stem cells (ESCs) are rapidly emerging as a promising cell source due to their unique characteristics – namely their ability to readily proliferate in culture as well as their potential to differentiate into all adult cell types. However, cell manufacturing and regulatory challenges must be overcome before clinical application of ESC therapies will be viable. One approach consists of predictive strategies via computer modeling methods to predict ESC culture outcomes based on various input parameters. To date, several groups have used mathematical modeling and analysis techniques to describe cell proliferation and differentiation based on uncertain cell, substrate, fluid, and fluid flow characteristics e.g. population, wettability, and concentrations, respectively. Here, we explore fractal analysis to characterize cell growth as indicated by cell culture morphology.

Introduction

Two cell lines were used for these experiments. Mouse ESCs (D3 line) were grown in static six-well plates in DMEM +10%FBS at 37°C and 5% CO

Methods

2. Brightfield images were taken at 10 minute intervals over a 4 day period. Human ESCs (CA-1T line) were grown in static six-well plates in mTeSR on Matrigel at 37°C and 5% CO2

. Brightfield photos were taken at every cell count time point. Images were processed by using ImageJ software (NIH). Brightfield images were converted to binary ones and analyzed by using the FracLac fractal analysis plugin for ImageJ. The box counting method was used to evaluate fractal dimension. Multifractal analysis was also done to further characterize cell culture morphology.

The fractal dimension was determined for mouse ESCs over one passage and was found to increase at an approximately linear rate to a maximum value equal to about 1.8. As cell number and corresponding culture area increases at an exponential rate versus time, we conclude that the fractal dimension is indeed a function of cell morphological complexity.

Results

Future studies will include analysis of induction of differentiation to all three germ layers. Ultimately the ability to detect small changes in cellular complexity via fractal dimension may allow for better control over directed differentiation.

Conclusions

i. ii.

Figures iii.

Box counting to determine fractal dimension i) N=34 ε=200µm, ii) N=108 ε=100 µm, iii) N=418 ε=50 µm.

0

0.5

1

1.5

2

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 20 40 60 80 100 120 140 160 180 200

Fractal Dim

ensionViab

le C

ell D

ensi

ty(1

05ce

lls/c

m2 )

Time (hours)

Viable Cell Density Fractal Dimension 5x Top Plot: Comparison of fractal dimension and viable cell density over one passage of mouse ESCs. Bottom Plot: Comparison of fractal dimension and viable cell density over one passage of human ESCs.



Strain Measurement of Orthodontic Brackets using Digital Image Correlation Garrett W. Melenka, David S. Nobes, Jason P. Carey

Department of Mechanical Engineering, University of Alberta, Edmonton AB T6G 2G8

Introduction: Braces and archwires are commonly used by orthodontists to correct tooth misalignment (malocclusions). Tooth motion, in orthodontics, is achieved by applying forces and moments to the crown of the tooth with orthodontic brackets and archwires. Understanding the deformation of the brackets is required to improve treatment efficiency and to create an accurate model of the bracket- archwire- tooth complex1. The objective of this work was to design a contact free measurement system to observe and measure the wire/bracket interaction during rotation of an archwire within a bracket slot. Methods: We developed an optical strain measurement technique to allow for contact free strain measurement of orthodontic brackets. Using the concept of digital image correlation (DIC) to calculate the strain fields from images acquired using a high resolution camera2. With this method we can determine the two dimensional (2D) deformation of an object, such as an orthodontic bracket3 (Figure 1). To expand on the strain measurement of orthodontic brackets, we developed a stereo digital image correlation technique to determine three dimensional (3D) deformations between pairs of stereo images. We compared titanium and stainless steel brackets deformation versus wire angle of twist, among other tests, using the DIC method. Results: DIC results show that the stainless steel brackets exhibited greater plastic deformation than the titanium brackets indicating that material properties affect how the brackets respond to loads applied by an archwire (Figure 2). 3D imaging tests were performed on orthodontic brackets using a stereo microscope to quantify the in plane and out of plane motion of the brackets (Figure 3).

The development of this contact free strain measurement system will have immediate

Conclusions

applications in orthodontic design and procedures, as better modeling of tooth response to applied forces can be achieved. Tooth response can be used to create simulations that predict treatment outcomes and to design patient specific treatments. Beyond this specific application, 2D and 3D contact free strain- field measuring systems can be applied to engineering applications where direct strain measurement is difficult or impractical due to the geometry, complex loading conditions or scale of the components.

1. Archambault A., et al Angle Orthod, 80(1), 201-10.

References

2. Pan B et al, Meas. Sci. Technol

3. Melenka, GW, et al, Eur J Orthod (Accepted 2011-09-01)

, 20(6), 062001.

Figure 1: Deformation of an Orthodontic Bracket Caused by Archwire Rotation

Figure 2: Comparison of Titanium and Stainless Steel Orthodontic Bracket Deformation

Figure 3: Stereo Images of Brackets used for Deformation

Measurement



In-situ Chondrocyte Mechanics at Different Loading Rates: A Finite Element Study E.K. Moo1,2, W. Herzog2, S.K. Han3,2, N.A. Abu Osman1, B. Pingguan-Murphy1, S. Federico2

1 University of Malaya, Malaysia; 2 The University of Calgary, Canada; 3

University of Maryland, USA

Mechanical impact loading involving cell death is thought to cause osteoarthritis onset and progression [1]. In order to understand why in-situ cells die readily following impact loading but remain unaffected when the same load is applied at a slow rate, we used finite element modelling of articular cartilage and chondrocytes to study the in-situ cell mechanics (which cannot be measured experimentally due to technical limitations). The objective of this study was to investigate the effects of strain rates on in-situ chondrocyte mechanics. We hypothesized that differences in cell mechanics at different strain rates might point to the reason(s) for cells dying at high but not at low strain rates.

Introduction

A two-scale modelling approach was used to describe the cartilage tissue (macroscale model) and the embedded cells (microscale model) [2]. The tissue model consists of a layer of cartilage “mounted” on a layer of subchondral bone. The cell model consists of a chondrocyte surrounded by its cell membrane, pericellular matrix, pericellular capsule, and the neighbouring extracellular matrix

Methods

[4]. Both models are non-linear and biphasic with an isotropic hyperelastic potential and a void ratio dependent permeability [3]. The depth-dependent material constants were derived from published data [5]. Finite Element analysis was performed using ABAQUS v6.10. A confined compression test at 5% nominal strain was applied onto the articular surface at different strain rates (0.167-500 %/s). The calculated time-dependent variables of interest (deformation and pore pressure) were then applied as boundary conditions for the micro level cell model.

Cell deformations (fig. A) were highest at the impact strain rates, but did not reach failure levels. Tangential tensile membrane strain rates (fig. B) were highest at the highest loading rate and were observed primarily in superficial zone cells.

Results

Our results suggest that cell death in impact loading is caused by high tangential tensile strain rates in the cell membrane, causing membrane rupture and loss of cell integrity.

Discussion and Conclusion

[1] Blanco et al. 1998. Arthritis Rheum, 41(2): 284-289. [2] Guilak et al. 2000. J Biomech, 33(12): 1663-1673. [3] Holmes MH and Mow VC. 1990. J Biomech, 23:1145-1156. [4] Wu JZ, et al. 1999. J. Biomech, 32:563-572. [5] Wang et al. 2003. J. Biomech, 36(3): 339-353.

References

Acknowledgments: OA Team grant and ISB.



Susceptibility weighted imaging reveals lesions in a mouse model of multiple sclerosis Nabeela Nathoo, Ying Wu, Smriti Agrawal, Sarah Haylock-Jacobs, Samuel Barnes, Andy Obenaus, Tad Foniok,

Voon Wee Yong, Jeff F. Dunn Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB T2N 4N1

IntroductionMultiple sclerosis (MS) is an inflammatory, demyelinating neurological condition. In Alberta, 1 out of every 350 people is affected by MS. As there is no known cause for MS, the proposed theory of chronic cerebrospinal venous insufficiency (CCSVI) has gained considerable attention. CCSVI proposes that impaired venous drainage results in iron deposition in the brain and leads to the development of MS [1]. CCSVI is having a profound effect on the MS community, leading to a number of MS patients undergoing experimental endovascular treatment without validation of CCSVI by scientific studies. MRI methods sensitive to iron, such as susceptibility weighted imaging (SWI), have shown iron-related lesions in human MS patients [2,3]. We investigated if SWI shows iron-related lesions in the commonly used mouse model of MS, experimental allergic encephalomyelitis (EAE).

MethodsFemale C57BL/6 mice were induced with EAE using methods described previously [4]. A 9.4T MRI console was used for in vivo high-resolution 3D gradient echo with full flow compensation on the cerebellum and lumbar spine (n = 19) (image parameters: matrix=192x128x32, FOV=0.92x1.28x1.28cm, TE/TR=4/50, flip angle=15°).

Magnitude and phase MRI data were processed using SPIN software to create SWI images. A 32x32 Hanning filter was applied to phase images with a negative phase mask to show the susceptibility effects of iron. Phase data was multiplied into magnitude data 4 times to make SWI images. Prussian blue staining for iron was performed for correlation with SWI MRI. We also performed a study where mice were imaged in vivo using the same sequence and parameters as above, perfused, and then put back in the MRI for imaging using the same

sequence and parameters that were used pre-perfusion for in vivo imaging (n = 10). ResultsIn the lumbar spine, SWI lesions were observed in white matter, where some corresponded to iron deposition. Lesions were also seen at the grey/white matter boundary (G/WMB) of the spinal cord. Many G/WMB SWI lesions disappeared post-perfusion.

In the cerebellum, SWI lesions were seen in white matter tracts. These lesions corresponded to perivascular cuffs, where some were iron-related (Fig. 1). Many of these lesions disappeared post-perfusion.

ConclusionsOur data show that SWI lesions exist and are regionally specific in the EAE mouse. Some SWI lesions are iron-related, but many are associated with the vasculature. These lesions may originate from hypoxic or inflamed veins. EAE is not induced by venous occlusion, but rather is an inflammatory model with a phenotype similar to that seen in MS. The presence of SWI lesions in EAE is not specific to venous occlusion during induction of disease.

[1] Zamboni, P. et al. J Neurol Neurosurg Psychiatry 80, 392-399 (2009).

References

[2] Haacke, E.M. et al. J Magn Reson Imaging 29, 537-544 (2009). [3] Eissa, A. et al. J Magn Reson Imaging 30, 737-742 (2009). [4] Agrawal, S. et al. J Neurosci 31, 669-677 (2011).

12

34

5

1 2 3

a

b

c

Figures

befo

re p

erfu

sion

afte

r per

fusi

on

Figure 1. SWI lesions

in the cerebellum correspond to perivascular cuffs.

Figure 2. SWI lesions seen pre-perfusion disappear post-perfusion.



Contribution of the upper body to a unique gait transition in cross-country skiing Anthony Killick, Sean Crooks, Haakon Lenes, Walter Herzog

University of Calgary

Introduction With increasing speeds of locomotion, animals change their gait pattern to minimize metabolic cost. For example, a horse will walk at low speeds, trot at intermediate speeds, and gallop at high speeds (1). Similarly, cross-country skiers use the two-skate technique at low speeds, transition to the one-skate technique at intermediate speeds, but then, contrary to everything known about gait transitions in two-legged and four-legged locomotion, skiers revert back to the two-skate technique at very high speeds. The difference between the one- and two-skate techniques is defined by the coordination of the poling cycles performed with the arms and the skating cycles performed with the legs. In the one-skate technique, poles are planted simultaneously with every skate stride, while in the two-skate technique, poles are planted with every second skate stride (2). Previous data from our group showed that the transitions from two- to one- and back to the two-skate pattern are indeed associated with trying to minimize the cost of transport, defined as the oxygen uptake required per distance traveled. The purpose of this study was to explain how the two-skate technique has a lower cost of transport than the one-skate technique at very low and very high, but not at intermediate skiing speeds.

Four trained cross-country ski racers performed two separate tests for each technique of skate skiing. First, subjects skied at 6, 15, and 30 km/h on a rollerski treadmill. These speeds were selected because the differences in oxygen cost between the two techniques were found to be greatest at these speeds in previous testing. During the entire test, oxygen uptake, forces transmitted by the skiers through the poles, blood lactate concentration, and 3-dimensional, high speed kinematics, were recorded for one technique and repeated on a separate day using the second technique.

Methods

In the second phase of testing, the metabolic cost of the poling motion was determined on a pole ergometer with subjects matching their stroke rate and poling forces using video and force feedback. These tests were performed for all speeds and both techniques tested in the first set of rollerski tests, while also measuring oxygen uptake. Leg movements were limited by bracing of the knee and ankle.

Oxygen uptake was similar for roller skiing at 6 and 15km/h. However, at 30km/h, oxygen uptake for the one-skate technique was significantly greater (4 ml/kg/min) than for the two-skate technique. The average metabolic cost associated with the upper-body work alone was 66, 63, and 60% of the total body oxygen uptake at 6, 15, and 30 km/h respectively for the one-skate technique and was 61, 56, and 57% for the two-skate technique. On average, metabolic cost of the upper body was always higher for the one-skate compared to the two-skate technique.

Results

Skiing at 6 and 15km/h requires the same metabolic energy in the one-skate and two skate techniques, although the arms and poles seem to contribute more to propulsion in the one-skate than the two-skate technique, based on their metabolic requirement. However, at 30km/h, the one-skate technique requires more metabolic cost than the two-skate technique. Since the skating action with the legs is similar between the one- and two-skate techniques, but the arm action occurs at a much higher frequency in the one- compared to the two-skate technique, we propose that it is primarily the arm action that limits efficient skiing at high speeds in the one-skate technique.

Conclusions

(1) Hoyt et al., Nature, 292, 240, 1981. References

(2) G. Smith, in Handbook of Sports Medicine and Science: Cross Country Skiing, H. Rusko (Blackwell Publishing), 2002, p. 32-60



A Pressure Control System for Brace Treatment of Scoliosis E Chalmers1,2, E Lou 1,2, D Hill2, V Zho1, MS Wong3

1Department of Electrical & Computer Engineering, University of Alberta, Edmonton AB Canada 2Glenrose Rehabilitation Hospital, 10230 11 Ave, Edmonton AB Canada, T5G 0B7

3

Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong

Adolescent Idiopathic Scoliosis is a deformation of the spine involving abnormal curvature and vertebral rotation. It affects 3% of the population [1]. Bracing attempts to avoid corrective surgery by preventing curve progression, and is the most commonly used non-surgical treatment. Controlled studies of bracing show high success rates, but in practice two problems are encountered: wear-time is often unknown, and brace tightness can fluctuate with activity [2]. This paper reports the development and validation of a system to monitor brace wear-time and control brace tightness.

Introduction

The system consisted of four monitor-regulator units to be installed at key pressure points in the brace. Each unit included a microcontroller system, an inflatable air bladder, and a gauge pressure sensor. A closed control loop used feedback from the sensor and inflated/deflated the bladder to regulate the pressure applied to the patient’s body. The algorithm was designed for good performance in real conditions, while avoiding too-frequent or unnecessary pressure adjustments. The unit monitored brace wear-time by sensing the patient through a breathing detection algorithm applied to pressure readings. The system was designed to be small, for low power consumption and minimal user interaction.

Methods

Four healthy subjects wore an instrumented brace for 2 hours without pressure regulation and 2 hours with regulation. Each test began with target pressure at 5.3 kPa, and the percentage of pressure readings falling in a target range of 5.3 ± 0.67 kPa was calculated. The brace wear-time logged by the system was also compared to the actual wear-time recorded by the subjects.

Enabling the system decreased the amount of time spent below the target range for all four subjects (Fig 1). On average the percentage of pressure readings in the desired range doubled (from 31% to 62%). The measured brace wear-time agreed with subject’s records in all cases. Each unit could run for one month on a battery charge, and log pressure readings for one year. The units did not reduce the comfort of the brace or affect the patient’s activities.

Results

The pressure control system improves the consistency of brace pressure, and accurately monitors brace wear-time. These results indicate that the system should improve brace treatment effectiveness.

Conclusions

[1] Lonstein J, “Adolescent Idiopathic Scoliosis”, lancet 1994, 344(8934): 1407

References

[2] Mak I, et al. “The effect of time on qualitative compliance in brace treatment for AIS”, Prosthetics & Orthotics International 2008, 32(2):136-144.

Fig 1. Test results showing the system’s ability to increase time spent in a desired brace pressure range.



Cartilage Boundary Lubricating Ability of Aldehyde Modified PRG4 1Abubacker, S;

2Ham H O;

2Messersmith, P B; +

1Schmidt, T A

+1University of Calgary, Calgary, AB, Canada;

2Northwestern University, Evanston, IL, USA

Introduction Proteoglycan 4 (PRG4) is a

mucinous glycoprotein present in synovial

fluid and at the surface of articular cartilage

where it functions as a critical boundary

lubricant necessary for joint health1. A

recent study, motivated by diminished PRG4

levels associated with early osteoarthritis

(OA), demonstrated aldehyde (CHO)

modification of PRG4 significantly

enhanced its binding to a depleted articular

surface2. However, it remains to be

determined if CHO modification alters the

friction-reducing ability of PRG4. Hence,

the objective of this study was to assess the

cartilage boundary lubricating ability of

CHO modified PRG4 (PRG4-CHO).

Methods PRG4 was prepared by purification

from media conditioned cartilage explants

from bovine stifle joints, as described

previously3. PRG4-CHO was prepared using

succinimidyl 4-formylbenzamide (CHO) at a

PRG4:CHO molar ratio of 1:1000 in

100mM PO4 buffer as previously described2.

A treatment control (PRG4-SHAM) was

exposed to modification buffers and

incubations in the absence of CHO. PRG4

samples were prepared at a physiological

concentration of 450 μg/mL3 in phosphate

buffered saline (PBS). PBS and bovine

synovial fluid (SF) served as negative and

positive controls, respectively. Each

lubricant was assessed using a previously

described in vitro cartilage-on-cartilage

friction test under boundary lubricating

conditions3. Static (μstatic,Neq) and kinetic

() friction coefficients were then

calculated3.

Results All PRG4 preparations functioned as

effective friction-reducing cartilage

boundary lubricants. Lubricants and Tps

(pre-spin durations) modulated friction.

μstatic,Neq varied with Tps and test lubricant

(both p

Update on clinical feasibility of the Smart-e-Pants for prevention of deep tissue injury 1Alisa Ahmetovic, 1Lisa Kawasaki, 2Dana Schnepf, 3Ryan Sommer, 1,4Vivian Mushahwar, and 1K. Ming Chan

1Centre for Neuroscience, Univ Alberta, 2Allen Gray Continiuing Care Centre, Glenrose Rehabilitation Hospital, 1,4

AHFMR Interdisciplinary Team in Smart Neural Prostheses Dept. Cell Biology, Univ Alberta, Edmonton, AB, Canada

Introduction Pressure ulcers around the ischial tuberosities are common in people with impaired mobility. They result from muscle ischemia and breakdown caused by prolonged loading and deformation. Our group showed in rats that intermittent electrical stimulation (IES) prevents the formation of deep tissue injury (DTI) - pressure ulcers of deep origin. In addition, we showed that IES redistributed pressure and increased oxygenation in the loaded muscles. This work led to the development of the Smart-e-Pants system for the prevention of DTI in human patients. The goal of this study is to test the feasibility of Smart-e-Pants in 2 settings: a long term care facility (LTCF) and a rehabilitation hospital (RH). We reported our preliminary ‘system component testing’ results at the BME 2010 conference for 3 subjects at LTCF. We have since tested the complete system in a greater number of subjects.

Methods Smart-e-Pants system (Fig. 1) is comprised of surface electrodes, a garment to secure the electrodes on the skin, and a stimulator with data logging capabilities. With the stimulating electrodes placed on the motor points of the gluteus maximus muscles, open loop stimulation at 17.5 Hz is triggered every 10 minutes for 10 seconds. Study protocol: Subjects who are cognitively competent with intact skin and body mass index

Expansion of Skin-Derived Precursor (SKP) Cells to Promote Nerve Regeneration Evelyn Heik

1, Holly M. Wobma

1, Jochen Fahr

1, Rajan Kumar

2, Jeff Biernaskie

2, Raj Midha

3, Michael S. Kallos

1

1Pharmaceutical Production Research Facility (PPRF), University of Calgary, 2500 University Dr NW, Calgary AB

2Department of Comparative Biology and Experimental Medicine, 3330 Hospital Dr NW T2N 4N1

3Department of Clinical Neuroscience, 3330 Hospital Dr NW T2N 4N1

Introduction: The current standard for

treating peripheral nerve damage is to take a

piece of nerve from another region of the

body and use it to suture the free nerve

endings at the damaged site1. Because of the

often low-integrity and scarcity of these

donor nerves, it is desirable to come up with

alternative treatment methods. One option is

to regenerate the damaged nerve using stem

cell-based therapies. Encouragingly, in

recent years, a type of skin-derived stem cell

(SKP) has been identified, which can

differentiate into Schwann cells and promote

nerve regeneration in animal models2,3

.

To use SKP cells in the clinic, it is important

to be able to produce them in sufficient

quantities. Bioreactors may be able to be

used for this purpose4; however, they require

a threshold number of cells before they can

be used. To address this, we have been

exploring methods to initially expand SKP

cells in static culture. As with other neural

precursors, SKP cells grow as spheres of

cells, which must be dissociated to single

cells for passaging2. There are several

dissociation methods, including chemical

and enzymatic. For this study, our aim was

to identify which of the methods would lead

to the highest cell growth and viability, and

the best retention of the SKP cell phenotype

(spherical aggregates) vs. differentiated cells

(attached to the dish).

Methods: SKP cells were cultured in SKP

proliferation media at 37°C and 5% CO2 in

T-25 and T-75 flasks. Enzymatic

dissociation was investigated using

Collagenase XI, 0.05% Trypsin-EDTA and

Accutase. Chemical dissociation was

performed by exposing cells to basic

medium (pH 11.7) followed by

neutralization with acidic medium (pH 2)4.

Following aggregate dissociation, cell

counts and viability were determined using a

hemocytometer. Microscopy was then used

to reveal cell morphology, an indicator for

SKP cell phenotype. Dissociated cells were

then cultured for 12 days and the fraction of

unattached cells (i.e. SKP cells) was

measured.

Results: All three enzymes successfully

dissociated cell aggregates. Cells treated

with Trypsin and Accutase tended to adhere

to the culture flask surface and subsequently

differentiate into fibroblast cells, whereas

treatment with Collagenase XI led to round,

free-floating aggregates, high growth rates,

and, importantly, high viabilities. Figure 1

illustrates the fractions of free-floating

(SKP) and adherent (differentiated) cells

following treatment. It was also found that

chemical dissociation did not break up SKP

cell aggregates.

Figure 1: Portion of cells in the washed fraction

compared to the attached cells over 12 days.

Conclusions: Our data show that cell

dissociation using Collagenese XI best

promoted cell viability and growth, while

maintaining the SKP cell phenotype. This is

an important first step in producing

therapeutically relevant quantities of SKP

cells in bioreactors for therapeutic use.

References: 1. Evans, G.R.D. Anat. Rec. 263, 396-404

(2001). 2. Biernaskie, J. et al. J. Neurosci. 27,

9545-9559 (2007). 3. Walsh SK, Biernaskie J,

Kemp SWP, Midha R. Neuroscience 164, 1097-

107 (2009). 4. Sen, A., Kallos, M.S. & Behie,

L.A. Tissue Eng. 10, 904-913 (2004).



Development of a Long-Term Wheelchair Propulsion Instrumentation Device for Use inEvaluating Community Ambulation Parameters

Kenton Hamaluik, Jiajie Wu and Martin Ferguson-PellFaculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada

AHFMR Bone and Joint Health Team GrantIntroductionThe reported prevalence of overuse injuriesand chronic pain in the shoulders and upperextremities of long-term manual wheelchairusers (MWUs) ranges from 30-60%. Failureto achieve functional goals due to exertionalchallenges of wheelchair use are unknown,but likely to be a cause of significant socialisolation. Boninger et al (2005) and Merceret al (2006) have demonstrated a directcorrelation between extended exertionrelated to manual wheelchair propulsion andpain and injury. A widely adopted methodfor measuring the exertion levels of MWUsis the SmartWheel (SW) (Three Rivers, AZ).SWs are instrumented manual wheelchairwheels capable of directly measuring theforces and torques applied to the rim duringpropulsion. While SWs are an excellent toolin a clinical setting, they are not well-suitedto community ambulation studies as they areintended for brief periods of measurement.In principle, by recording kinematicparameters of manual wheelchair propulsionsuch as velocity, acceleration, and cadence,the application of Newton’s laws of motionshould allow the direct calculation ofpropulsion forces - significantly simplifyingthe monitoring technology and allowing itbe packaged for relatively low cost fordeployment on any manual wheelchair foran extended period of time in the user’s real-life environment.MethodsA custom fabricated measurement andrecording system (“Tachyon”) wasdeveloped to measure key wheelchairperforamance parameters: wheel velocity,pitch, yaw and roll, heading, ambientconditions (temperature and humidity) andheart rate. The Tachyon system can alsowirelessly communicate with a 6 degree offreedom inertial measurement unit (IMU)and potentially a GPS unit. The IMUmeasures internal movement of thewheelchair user’s upper body relative to thewheelchair base, which affects stability and

propulsion biomechanics. All data iscollected continuously and streamed to anSD card for later retrieval and analysisResultsThe Tachyon units performed as designedand record all information accurately andsuccessfully. By sending the Tachyon unitsto sleep when the wheelchair user wasinactive, the Tachyon device was able tooperate autonomously without beingcharged for approximately 5-6 days, a lengthof time that is acceptable for collectingcommunity ambulation data. Estimatingpropulsion forces using wheelchairdynamics has proved to be more complexthan anticipated. Upper body inertial effectscontribute significantly to instantaneousacceleration readings, thereby confoundingestimates of propulsion forces. Models arebeing developed using the IMU to accountfor these effects. In the meantime Tachyonis proving very effective in collecting “realworld” data that can be used to develop‘biomechanical virtial reality scenarios’ thatcan be ‘replayed’ in the laboratory whereSmartwheel technology and motion capturecan be deployed for accurate measurementof propulsion biomechanics.ConclusionsTachyon collects a rich array of data onwheelchair propulsion in communitysettings. It also has to the potential to studybiomechanics of wheelchair propulsion forelite wheelchair athletes. Collecting data toinform the design of biomechanicallyrealistic virtual scenarios is opening upinteresting opportunities to studyperformance and factors influencing overuseinjuries in long term wheelchair users incommunity ambulation settings.ReferencesM. Boninger, A. Joontz, S. Sisto, T. Dyson-Hudson, M. Chang, R. Price, and R. Cooper.Rehab.Res. Devel. 43:9-19, 2005.J. Mercer, M. Boninger, A. Joontz, D. Ren, T.Dyson-Hudson, and R. Cooper. Clin. Biomech.,21:781-789, 2006.



Investigations of Intercellular Communication in a 3-Dimensional Scaffold Swathi Damaraju, Neil A. Duncan

McCaig Institute for Bone and Joint Health, University of Calgary

Cells cultured in 3D scaffolds can better mimic their physiological environment

Introduction

1. It is well established that there is an interconnected relationship between connexin containing gap junctions, cadherins, and integrins in bone cell communication and the response of bone cells to mechanical stimulation2. Using this knowledge, in-vitro 3D stem cell culture models for ex-vivo bone tissue investigations can offer insight into the role of cell communication in the healing of bone defects1,2

. The aim of this work was to determine the activity and presence of cadherins and connexin containing gap junctions in murine embryonic stem cells seeded in a three dimensional collagen scaffold.

Murine embryonic stem cells were maintained in T75 culture flasks, and after 3 to 4 passages, 1 million cells were spun down and re-suspended in media containing pro-osteoblastic-gamma-carboxyglutamic acid-containing protein (BGP) (260mg/ml of media). The suspension was combined with purified bovine collagen I (Advanced BioMatrix), seeded in 24-well plates, and incubated at 37°C for 5, 15, 20 and 30 days. At each time point, fluorescence recovery after photobleaching (FRAP) was performed with and without communication blockers. Octanol was used as a general communication blocker, and 18-alpha-glycyrrhetinic acid (AGA) was used as a specific and reversible gap junction blocker. Immunofluorescence for osteoblast-cadherin, connexin-32, and connexin-43 was performed. A Zeiss LSM510 confocal microscope was used for all imaging.

Methods

Differences between average maximum percent recovery in early (day 5) and late (days 15, 20, and 30) differentiated murine osteoblasts was significant at α = 0.05 (Fig.

1). Octanol and AGA treatment significantly blocked gap junction activity (Fig. 1). Immunofluorescence showed increased presence of osteoblast-cadherin, connexin-32, and connexin-43 in day 15, 20, and day 30 differentiated murine osteoblasts than day 5 (Fig. 2).

Results

The results from the current study demonstrate that murine embryonic stem cells guided to differentiate into osteoblasts in a collagen I construct increase gap junction activity and presence of connexins and cadherins as differentiation progresses. Future studies using these cell-gel scaffolds will provide an understanding of the importance of intercellular communication to the proliferation of embryonic stem cells in an ex-vivo bone fracture, and the role of mechanical stimulation in the healing process of bone tissue.

Conclusions

1. Thompson et al. In-vitro models for bone mechanobiology. ProcIMechE,224:1533–1541, 2010.

References

2. Grimston et al. Role of connexin-43 in osteoblast response to physi

12th annual...: dr. michael kallos & dr. samer adeeb kinnear centre kc 103 saturday 7:00 – 8:00 am...

Documents